6. DATA VISUALIZATION

This chapter corresponds to the Marine Environment section of Web version of the Atlas.

6.1. Physical Characteristics

The processes of ice melting, water mass vertical structure, and thermal characteristics of the marine environment determine the dynamics of the Kara Sea and the Barents Sea plankton development. The present section provides the information on ice edge climatology, water vertical structure, and temperature and salinity fields.

Ice

the web version of the Atlas contains maps characterizing the mean ice edge position for the middle of each month (Eastern-Western Arctic Sea Ice Climatology, 1984).

Temperature and Salinity

The objective data analysis procedure used for this work generally corresponds to the scheme suggested by Barnes (1973) and the methods for calculating the data spatial distribution and map plotting used by Levitus and Boyer (1994). Additions to the algorithm have been made to account for the anisotropic structure of oceanographic fields in the Barents and Kara Seas

For the calculation of temperature distribution fields at the surface of the Barents and Kara Seas, in the summer a correlation radius of 250 km is used and in the winter this radius was reduced to 180 km. At a depth of 100 m the radius is 35-40% less than at the surface. The values of temperature and salinity are calculated for the grid of 20 x 20 km for three time intervals: 1920-1940, 1950-1960, and 1980-1990. The choice of these periods is determined by the availability of plankton data, water temperature, and salinity data for these years. For each time interval the following searchable maps were constructed:

Barents Sea - temperature and salinity, surface and depth 100 m, winter and summer;
Kara Sea - temperature and salinity, surface and depth 100 m, summer.
Winter = {January, February, March, April}.
Summer = {July, August, September}.

The oceanographic data used for mapping of temperature and salinity were obtained from the database of the WDC (Silver Spring, MD, USA) and MMBI.

Vertical Structure of the Barents Sea

A great number of papers are concerned with the problems of the vertical structure of the Barents Sea. It is established that, in winter, the water temperature T(^oC) and density d (kg/m³) vary insignificantly with depth. In summer, in the layer of 30-80 m, sharp T and d gradients are observed as a result of the temperature rise in the surface water layer. The availability of temperature and salinity monthly climatic fields for the Barents Sea (Matishov et al., 1998) makes it possible to document the annual cycle of T and d variations in the vertical plane. The algorithm of computation of the vertical gradients T and d is comprised of several stages.

a) The climatic density fields were calculated for January, February, ..., December, based on the monthly climatic temperature and salinity fields on a 10' x 30' grid.

b) The fields characterizing the difference in the values of temperature (T) and density (d) at the horizons of 0 and 100 meters were calculated for each month:

T = T_0m - T_100m ;    d = d_0m - d_100m

c) The method of the objective analysis was used for mapping the T, and d values.

Using the HTML information system, the CD-ROM presents graphs and maps characterizing the annual cycle of variation of T and d values. The obtained results distinguish two time periods with the stable temperature and density structures: the winter and summer regimes. The duration of the winter regime is from January untill April. During this period the values of T and img src="../IMAGES/delta.gif">d reach an annual minimum. The duration of the summer regime is from July untill September. During this period, the values of T and d reach an annual maximum.

6.2. Biological Characteristics

The distribution fields (searchable maps) of abundance, biomass, and number of phyto and zooplankton species are used to describe the state of the planktonic communities. Coefficients of biodiversity, calculated based up on the above mentioned characteristics, are used in hydrobiological studies. These coefficients characterize the level of diversity in the plankton community. The rise in the biodiversity level is induced by additional energy in the ecosystem ( Legendre and Demers, 1985), the source of which is determined by the regional features of the investigated ocean region. For example, in the Kara Sea it can be the flux of the Atlantic waters coming from north or the discharge of the Ob or Yenisey rivers. In the Barents Sea it can also be the flux of Atlantic waters coming from the Norwegian Sea or an influx of fresh water resulting from ice melting ( Timofeev 1988). Thus, the fields of distribution of the plankton characteristics can be used not only as an indicator of the state of the plankton community, but also as a tool of study for water masses of the Barents and Kara Seas.

The Glisson coefficient is used as biodiversity coefficient (K_gl):
  K_gl = (N_t-1) / log(N_i) 
in which:

N_i - number of individuals,
N_t - number of species in the sample.

The CD-ROM database contains information on zooplankton collected from the vessel Nerpa in 1936 and from the R/V Dalnie Zelentsy in 1981. In 1981, zooplankton abundance was determined in ind./m³. For comparison of the data obtained during these cruises, we use the same units as zooplankton abundance of 1936 using the following scales ( Drobysheva et al., 1986):

Rare = 1-10 ind./m³
Common = 11-100 ind./m³
Abundant = 101-1,000 ind./m³
Very abundant > 1,000 ind./m³

The Marine Environment section presents fields of distributions of plankton characteristics in the vertical and horizontal planes.

Searchable maps demonstrate winter variation of phytoplankton characteristics, along the route of nuclear icebreakers from the Barents Sea to the Kara Sea and on their way home. These graphs exhibit the phytoplankton state in regions previously inaccessible for hydrobiological studies during winter.